ISSN:
1013-9826
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
High speed imaging with decent image quality is difficult because the available exposuretimes are very short, which leads to the usage of a large aperture. Unfortunately, large aperture alsodecreases the depth resolution of the system, which reduces the quality of the image. Thus thesource of illumination has to be able to output a high amount of energy in a very short time so thatthe aperture requirement can be relaxed. There are only a few Xenon flash lamps that fulfill therequirement of sub-microsecond pulses, so the natural choice would be to use lasers. However,when the target surface is rough, high degree of coherence causes black and white interferencepatterns known as speckle. The sensor might register irradiance values from zero to saturated state.Needless to say, this reduces drastically the quality of the image. There is variety of techniques forspeckle removal, ranging from chaotic laser states to digital signal processing [1-5]. In this paperwe discuss an alternative, namely LEDs, for this kind of illumination. The authors have performedsome experiments and theoretical modeling, and successfully demonstrated an illumination systembased on LEDs that can output enough energy to enable imaging with pulse lengths of 100 ns
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/56/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.364-366.827.pdf
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